1,720,978 research outputs found
Effects of 8-chloroadenosine 3',5'-monophosphate and N6-benzyl-cyclic adenosine 5'-monophosphate on cell cycle kinetics of HL-60 leukemia cells.
No full textSite-selective cyclic AMP (cAMP) analogues have been shown to inhibit growth and induce differentiation in several human leukemia cell lines. However, detailed studies of the effects exerted by cAMP analogues on cell cycle kinetics have been lacking. We have examined the effects of 8-Cl-cAMP and N6-benzyl-cAMP on the cell cycle kinetics of the HL-60 human promyelocytic leukemia cell line. A cell cycle study was performed by univariate DNA analysis after 24-72 h of treatment with noncytotoxic concentrations of 8-Cl-cAMP and N6-benzyl-cAMP capable of inducing 50-60% growth inhibition in these cells. HL-60 cells treated with 5 microM 8-Cl-cAMP showed no significant change in the cell distribution in the cycle as compared to the untreated control cells, whereas the treatment with 10 microM N6-benzyl-cAMP transiently increased the percentage of cells in the G0/G1 phase after 48 h, followed by a partial recovery at 72 h. Combined treatment with low doses of 8-Cl-cAMP and N6-benzyl-cAMP, each of which alone produced 20% growth inhibition, exerted a growth inhibitory effect of 65% and delayed increase of the G0/G1 phase by 72 h. To better understand the cell cycle effects induced by 8-Cl-cAMP, flow cytometric analysis of bromodeoxyuridine incorporation was also performed. 8-Cl-cAMP treatment exhibited a slowing down of the cell cycle; thus, the delayed appearance of the G0/G1 cell accumulation after combined treatment could be due to this effect of 8-Cl-cAMP on the HL-60 cell cycle. At a toxic dose, 8-Cl-cAMP brought about a G2M block, whereas N6-benzyl-cAMP brought about an increase of the G0/G1 compartment. G2M block produced by toxic doses of 8-Cl-cAMP was not related to its adenosine metabolite since 8-Cl-adenosine did not produce any specific block in the cell cycle. Our results show, for the first time, that these site-selective cAMP analogues could affect cell cycle kinetics at different points. These data may provide the basis for combination treatments involving cAMP analogues and other agents in the treatment of human leukemia
Structure sensitivity of vibrational spectra of mesoporous silica SBA-15 and Pt/SBA-15
No full textThe vibrational properties of mesoporous silica (SBA-15) were investigated by deep ultraviolet (UV) Raman and infrared spectroscopies with and without the presence of platinum nanoparticles in the mesopores that were incorporated by sonication. Raman and IR spectral line assignments were made by comparison to amorphous silicas. This procedure permitted identification of vibrations of longitudinal (LO) and transverse (TO) optical lattice modes, the presence of Si-OH, and vibrational modes associated with the presence of three-, four-, and six-membered siloxane rings. Hydraulic pressing of the mesoporous silica with pressure in the range 3-7 tons cm(-2) destroys the X-ray diffraction pattern and strongly decreases the Raman peak (D-2) associated with three-membered rings at the surface. In the presence of platinum nanoparticles in the silica mesopores, a peak attributed to a Pt-O stretching vibration appears at between 530 and 580 cm(-1) in the UV-Raman spectrum, which can be used to monitor the presence of the platinum particles and their interaction with the support. The D-2 feature in the UV-Raman spectra also decreases with increasing Pt loading, which is attributed to interactions of the Pt nanoparticles with the silica surface.This work was supported by the Director,
Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, of the U.S. Department of Energy under
Contract No. DE-AC03-76SF00098. We thank Prof. E. Iglesias and B. Model for the use of their UV reflectance instrumentation.
Use of the National Center for Electron Microscopy for the TEM studies is acknowledged. K.Z. was supported by the
National Science Foundation under contract DMR-0244146. H.S. thanks the Korea Science and Engineering Foundation (KOSEF) for support under the Postdoctoral Fellowship Program
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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